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By E. F. Evoy

The uranium deposit of Gunnar Mines Ltd. is on south shore of Crackingstone Peninsula in the Beaverlodge area of northern Saskatchewan. The property spans St. Mary's Channel, a narrow waterway separating the mainland from a group of islands in Lake Athabasca. The mine property, consisting of 12 claims and 7 fractions, was staked in July 1952 by A. O. Zeemel and W. J. Blair. Diamond drilling commenced in the fall of that year and continued until the spring of 1954. In that interval, some 70,000 ft of drilling outlined an orebody plunging from the surface south-ward to a depth of 1000 ft below the shore of St. Mary's Channel. The last 9000 ft of drilling was through lake ice, and when this was interrupted by spring breakup, sufficient ore reserves had been established to warrant the present operation. Surface drilling was therefore terminated.

May 1, 1956

By Henry F. Adams, Guy H. Ruggles

In this paper the authors aim to chronicle the experience and salient points brought out in changing flotation reagents at a concentrator which had probably been using a minimum amount of oil at a minimum cost per ton, to a more complicated system requiring a partial chemical control. The original oils were coal tar and pine oil. The new reagents are lime, xanthate and pine oil. It was found that there were no insurmountable difficulties and eventually the cost of the new reagents per ton of ore proved to be very little more than that of the old. Lime Plant When the question of handling lime came up there were two propositions open: (1) to handle the lime dry; (2) to handle it wet in the form of an emulsion. Granting that a dry lime feeder would function properly, delivering lime uniformly, the chief objection was the dust that would be raised when these feeders were being charged or operated, as the only possible location was on a gallery beneath which men were working. With this objection the handling of lime as an emulsion seemed to be the better scheme. The lime plant which was first installed was for experimental work on one section. This was gradually changed and developed until it was of sufficient size to accommodate 20 sections. The various changes will not be discussed and the following description deals only with the fully developed plant. Crude as it is, and perhaps somewhat expensive to operate, the lime-handling plant has been quite successful. Much has been learned which will pave the way for a better installation in the future. Burnt lime is received loose in standard gage box cars. This is the product of the kilns and has had no screening or sorting. A grab sample is taken from each car as it is unloaded. An average of the analyses of samples from 44 cars gave the following: Available CaO Total CaO, Oxide and Hy- MgO, Fe²O³ + Al²O³, Insoluble, Per Cent. drate, Per Cent. Per Cent. Per Cent. Pek Cent. 88.3 79.2 1.6 ' 1.3 2.2

Jan 1, 1928

By Duk-Won Park

The PSU/MVS program, one of the computer programs for ventilation network analysis most recently developed at The Pennsylvania State University, was applied to the analysis of modifications to an existing ventilation system for a coal mine located in southern West Virginia. The program is well designed and has diversified capabilities which allow the users to make decisions on the optimum size and number of fans, the location and number of airshafts, and the optimum operational procedures. The mine had 10 working faces, from which the average production rate was about 5900 tons of clean coal per day. Two vane-axial mine fans were used in parallel at a shaft, and both of them operated simultaneously. One additional shaft was in the final construction stage and it would be used in four months to alleviate the load for the existing fans and distribute intake air more evenly. The overall ventilation surveys, including the altimeter pressure survey and the air quantity survey, were carried out in the mine entries, shafts, slopes, and gob areas. Computations were made using the above-mentioned computer program on the present condition and after one additional fan was placed in operation at the new shaft. Also, recommendations were made on the air route and fan blade settings for the most economical and efficient ventilation system. Further studies were carried out to decide the proper period when the third air shaft would be required according to the long-term mining plan. Additional branches were added for the next 4 years of the production plan, and the ventilation conditions were tested at the end of each year. Numerous combinations of blade settings and modifications of air routes were tested. It was recommended that the third air shaft be added at the end of the third year so as not to experience fan stall.

Jan 1, 1982

By G. H. Billings

There exists an unconfirmed opinion among many ironmasters that the combination of a small quantity of manganese, chromium, titanium, tungsten, aluminium, nickel, and some of the metalloids with iron has a beneficial effect upon the quality. And the impression prevails in some localities that the excellence of steel greatly depends upon the influence of some of these elements. Brit as the recorded experiments are so meagrely described, and made under such various conditions, the student in search of information upon the subject is somewhat bewildered by the contradiction of the opinions expressed. Observing some interesting phenomena while experimenting with an alloy of iron, copper, and nickel, I was led to determine the effect of some of the metals upon iron as free from contamination by other elements as it is possible to procure in practice, in order that the result of an alloy of an individual metal with iron might be more closely studied; for it is almost an impossibility to determine the influence of a small amount of one element upon a metal combined with a large amount of another, and the mere presence of another sometimes makes this difficult. And as most of the experiments recorded upon this subject have been made with iron containing sufficient carbon and other elements to interfere with the effect of that metal the influence of which it was desired to observe, I have endeavored to avoid these sources of error as far as practicable. In determining the specific gravity of the alloys in these ex-

By Elmer W. Pehrson

THE founding of the American Institute of Mining Engineers in 1871 came at an unusually significant moment in the life of our country. The industrial revolution, in which mineral production played a major role, was just getting underway. The iron industry, established several decades earlier, was reaching sizable proportions. In 1871 pig-iron production was approaching 2 million tons, and the industry had spread as far west as Missouri and Wisconsin. The chief sources of iron ore were Pennsylvania, New Jersey, New York, and Michigan. The age of steel was in its infancy; production had not yet reached 100,000 tons per annum. The gold rush to California two decades earlier and the discovery of other gold and silver bonanzas in the West paved the way for the transcontinental railways, which were then being built and which contributed much to the subsequent development of the great copper, lead, and zinc districts of the Rocky Mountain area. Regular production of copper in the Michigan peninsula and of lead in Missouri and the upper Mississippi region had been established for many years but on a scale dwarfed by the quantities later required as technical progress, invention and enterprise made possible the rapid expansion of industry. Discovery of oil in Pennsylvania in 1859, the growing recognition of the

Jan 1, 1947

By Charles H. Morgan

THE case of Henry Cort comprises: (1) the nature of Cort's inventions;, (2) their value to England and to mankind,; (3) the remuneration received therefor by him or his family; and (4) the suitable permanent record and recognition of his services by the representatives of the art lie founded-a debt long over-due, and still unpaid. I. CORT'S INVENTIONS. Under this head, it is unnecessary here to enter into details. The facts have been repeatedly published, and a brief outline of them will be sufficient for my present purpose. . Henry Cort, born in 1740 at Lancaster, England, became a navy broker in. London about 1765, and gained from that business in about ten years. something more than £20,000, which lie devoted to perfecting the manufacture of iron, building a mill at Fontley, near Portsmouth, and prosecuting, between 1777 and 1783, the experiments which culminated in .his two patents, one for puddling iron and the other for shaping it by rolling between grooved rolls.: Careful study of the contemporary evidence, including Cort's specifications, the testimony (in act as well as word) of his business rivals, the public declarations of eminent authorities, and the history of the times, leaves no possible doubt that Cort was the real inventor, of

Mar 1, 1905

By E. D. McMurry

INTRODUCTION Before discussing the use of the free piston; it may be well to explain briefly the type of gas lift valves with which the loo] is designed to function. The gas lift valve ii nothing more or less than a small back pressure regulator. It; construction consists of an outer hous ing covering a seamless metallic bellows in such a way as in form a sealed pressure vessel or pressure dome. To the bellow* in attached a stem and to this stem is attached a .rating member. When the valve is run into the hole, a pre-delermined pressure charge is placed in the pressure dome. As shown in Fig. 1. the valve is furnished in four different major assem-blies. to accomplish good results in different types of wells. The valve is mounted on a pup joint (Fig. 2a) : the eoin-plele assembly is entered into the tubing siring at the desired location. Each valve is furnished with a revere flow check valve (Fig. 2-b) to eliminate any back wash through the mechanism. Valve action is as follows: At any time the casing pressure is allowed to exceed the pressure forces within the pressure dome of the valve, the valve simply opens and passes gas from the rasing annulus into the tubing. When the casing pressure forces arc allowed to bleed to a force less than the pressure force within the dome, of the valve. the valve closes. With this type of construction. it is possible to open and close the valve or valves at will from the surface, the medium of the gas pressure in the rasing annnlus. The cycle of operation is governed by a tine cycle motor valve, commonly referred to as a gas lift interutitter or gas life surfacr controller (Fig. 3). In actual practice. after the well is unloaded only one valve is in operation . . . all other valve.: remain in the closed position. On pre-determined time cycles, it is possible to open and close this operating valve at will, and to pass the desired amount of gas through this valve wheneler needed. This method of gas lift is widelv used and has been found In be very efficient. However, it has long been known that even greater efficiency would be obtained if it were possible to place Piston between the injected gas and the fluid head. The free piston which will be discussed here was designed to accomplish this end and has been found to do so with very satisfactory results. DESIGN AND OPERATION OF THE FREE PISTON Basically. the free piston consist- of a telescoping assembly in which are incorporated the various control and operating parts (Fig. A set of sleeve valves which are opened and closed by movement of the telescoping section is contained in the. tool. A cross section of the free piston is shown in Fig. 4-11, 'rile main body cotain- a seamless monel bellows of the same type as that generally used in pressure charged gas lift valves (Fig. 4-c), and a valve core to permit placing a pressure charge in the bellows before the free piston is placed in service. The bellows is the main control unit of the free piston and performs two function: 1. It governs the opening and closing of the sleeve valves. a.: dictated by the producing activities of the well in which the piston is operating. 2. In its normal position, it holds a rubber packer in an elongated position to permit passage of fluid between the packer and the tubing walls. The lower section of the free piston contains a hydraulic shock absorber which cushions the return of the tool to its

Jan 1, 1953

By Steven Mitchell

BACKGROUND Homestake Mining Company began milling operations at the Bulldog Mountain Mine near Creede, Colorado in 1969. The Bulldog Mill, rated at 350 tpd, produces a bulk flotation condentrate assaying about 180 oz/T Ag and 20% Pb, from heads of about 16 oz/T Ag and 2% Pb. The circuit is straightforward with two-stage grinding to 1-5% plus 65 mesh, followed by rougher and cleaner flotation. Reagents used are Z-6, Z-11, Aerofloat 242 and Aero Promoter 404, with an Aerofroth 65-MIBC mixture for a frother. Additional information on the geology, mine and mill are available in references (1) and (2). A flow sheet for the mill and CIP plant together is attached as Figure 1. Final flotation tailings normally vary from 1.5 - 2.0 oz/T Ag. These tailings are cycloned to produce sand for underground backfill. After cycloning, the sands are repulped and given a final scavenger float. This sand scavenger recovers a small additional amount of silver which recycles back to the main flotation circuit. The tailings are recycloned and pumped to the mine or, if the mine cannot accept sand, to tailings. The majority of the silver in the flotation tailings exists in the fine fractions; cycloning upgrades the slimes and lowers the assay of the sand. The sand, after scavenging, typically assays 0.5 oz/T Ag, and the slimes assay about 3.0-3.5 oz/T Ag. From 1969 to 1976 all of the slime tailings and the sand tailings not used underground were impounded in a tailings pond located about

Jan 1, 1983

By Harold L. Overton, Leonard B. Lipson

The first paper in this series1 outlined practical methods for applying the theory of steady-state flow of an ideal Bingham plastic liquid through a circular pipe and axially through a stationary concentric annulus to the enginekring analysis of friction loss problems. In the present paper the properties of another useful rheological model, the pseudoplastic generalized Newtonian liquid, are considered. The terminology applied to the rheological models is derived from the following classification of rheological models. The term "generalized Newtonian" is a class designation applied to models which do not have yield points but which exhibit a dependence on shear rate. The term "pseudoplastic" applies to a sub-group of models within this class which exhibit a decrease in "viscosity" with increasing shear rate. The term "power model" refers to a mathematical model proposed for describing the behavior of the pseudoplastic liquid. This model is of interest since certain of the salt saturated, oil emulsion, and "low solids" drilling fluids, inverted emulsion- and oil-base drilling fluids, aqueous gels, gelled crudes and blocking agents employed in hydraulic fracturing operations are of this type. The present treatment considers the equations describing steady-state Poiseuille flow through a circular pipe and a stationary concentric annul us, and Couette flow between concentric rotating cylinders for a particular pseudoplastic model. As in the previous paper' it is demonstrated how these equations can be applied to engineering calculations of friction losses. Graphical procedures for recovering the various flow curves and cxample calculations are included. A method for simplifying turbulent-flow correlations is also proposed. PROPERTIES OF PSEUDOPLASTIC GENERALIZED NEWTONIAN LIQUID In contrast to the Bingham plastic the generalized Newtonian liquid is yield point-free. However, in the flow region the relation between stress and rate of shear is not linear as it is with ordinary Newtonian fluids. If the stress increases with shear rate at a less than linear rate the system is called pseudoplastic. While there is no yield point in this system, the Bingham advocates' coined the term pseudoplastic to distinguish this kind of behavior from Bingham plastic behavior. For the pseudoplastic a plot of flow rate vs friction loss or rpm vs torque, from pipe flow or rotational viscometer measurements, respectively, generally has three qualities: (1) it can be clearly extrapolated toward the origin; (2) there is very little slope at the origin. This accounts for the high apparent viscosities at low mixing and pumping rates; and (3) the flow curve possesses a continuous curvature which gradually diminishes as the shear increases. Rheological measurements on a pseudoplastic liquid can be easily misinterpreted as indicating Bingham plastic behavior. A typical case in point is illustrated in Fig. 1. These data were obtained from measurements on an oil-emulsion mud using a commercially available rotational-type viscometer (Model 35 Fann V-G meter). Applying the "two-point"* method3 gives a plastic viscosity of 17 cp and a yield point of 24 lb/100 ft2; at the same time weighting material settles very easily in this system. This illustrates that it is not possible to distinguish between the pseudoplastic and the Bingham plastic from only two data points. It is possible to determine qualitatively which model is more appropriate by a combination of dynamic and static measurements. Experience indicates that the simplest criterion for the Bingham plastic liquid is that the calculated dynamic yield point should be of the same magnitude as the measured gel strengths. For the oil-emulsion drilling fluid illustrated in Fig. 1, a value of 4 lb/100 ft2 was obtained for gel strengths measured

By F. Rosenblum, P. Spira, F. Kitzinger

The possibility of increasing the efficiency of mineral processing plants by means of computer control has prompted metallurgists to examine their flowsheets more critically in order to develop practical control strategies. Control schemes in use to date generally rely on the automation of traditional and previously manually regulated control loops, e.g., the addition of reagents to maintain a constant assay or a constant pH. This approach is predicated on the availability of well established primary sensors such as pH electrodes or on-stream analyzers. Noranda Research Center, in cooperation with Noranda Group concentrators, has developed a froth level monitor and a pulp density meter adaptable to this type of control. Although some of the basic principles on which they are based have been known for some time, their incorporation into the design of reliable, direct-reading instruments which can be interfaced with a computer is believed to be novel.

Jan 4, 1979

By E. F. Poncelet

Forty years ago A. A. Griffith developed a theory explaining why brittle materials displayed such low tensile strengths.' He based his views on two points. First, he found himself compelled to assume that all brittle materials are replete with flaws, cracks, and other defects that act, although quite invisible, as large stress raisers. Second, he applied the "theorem of minimum potential energy," which says that the total potential energy of a system must pass from the unbroken to the broken condition by a process involving a continuous decrease in potential energy. By this means he satisfactorily accounted for the noted low strength of such solids and also for the wide spread obtained in experimental measurement of these strengths. So successful has the theory been that it is favored by some to this day. Unfortunately this theory is of limited use beyond the explanation of these two noted phenomena and it is keenly felt that a better theoretical insight into the physics of the fracturing process is needed as the volume of experimental evidence accumulates. The author proposes in the following to build on the fundamentally sound concepts of Griffith and, with the help of increased theoretical knowledge over that available to Griffith, develop a mechanism for frac-ture which will provide far greater understanding of the experimental evidence accumulated to date than is possible from the original Griffith idea. THE GRlFFlTH THEORY Very little progress indeed can be made without accepting the first postulate of Griffith which supposes all brittle solids to be full of microcracks. It would be difficult indeed to find a better mechanism for the small strength of such brittle materials, in conjunction with the fact that the energy that must be expended for comminution is by no means small. The postulate of the existence of the microcracks permits the breakup of the various bonds a few at a time by concentrating the stress at the tip of the progressing crack, while the total energy expended is the same as if they all had been ruptured simultaneously. The only flaw in the argument is that no reasonable explanation has been proposed to account for the genesis of such cracks. Indeed their very presence is in violation of the Griffith second postulate, the potential energy theorem. This theorem is straightforward for isothermal processes, and, in spite of Griffith, there is some doubt that treating the problem isothermally is legitimate. The surface energy of bodies is a free energy, not a potential energy as stated by Griffith, and the production of new surface free energies is not necessarily an isothermal process. There is ample evidence to the contrary. Generally speaking, if heating a body increases its surface area, then, by virtue of Le Chatelier's principle, any increase of that area by other means will tend to lower its surface temperature. Lord Kelvin calculated the actual cooling that resulted in drawing out a film of liquid.2 R. A. Houston calculated the surface cooling that resulted in stretching a metal wire.3 These calculations were made by applying the Carnot cycle to the process and evaluating the thermodynamics thereof. IRREVERSIBILITY OF THE FRACTURING PROCESS While Griffith was very careful not to say so, the impression gained from studying his papers is that he considered the fracturing process as reversible, that is, a succession of quasi-equilibrium states. There is ample evidence that it is not. The indication that the new surfaces produced by the propagation of a crack are cooler than the original body points to an irreversible heat flow from the interior to the new surfaces to equalize the temperatures. If the process be reversible, any crack accidentally formed should immediately close up as, in the absence of any strain energy, the potential energy would thereby be lowered. The fact that they do not, constitutes a paradox. Such paradoxes are nothing new where certain phenomena that propagate from minuscule nuclei are assumed to be reversible. Such is, for instance, the condensation of a pure saturated vapor that is suddenly chilled by adiabatic expansion. At the beginning the tiny droplets that are formed should be only a few angstroms in size, but the vapor pressure at such droplets is so high that they should evaporate at once. A similar situation arises if a saturated pure solution becomes super-saturated upon cooling; the first tiny crystal nuclei should dissolve as fast as

Jan 1, 1964

By Ira Joralemon

THE sampling of disseminated copper deposits has been described often but the method of combining assays, to give the true shape and value of the orebody as it will be mined has received less attention. As the ore mined during five or ten years at several of the great disseminated properties has averaged materially lower in grade than the published estimates, the question of the sampling and estimating of these orebodies seems timely. In this paper, attention is given particularly to factors that may cause errors in the final estimate. Sampling of diamond-drill holes, churn-drill holes, and underground workings is briefly described in the first part of the paper; then the method of combining assays to give the average grade and tonnage that will be mined is taken up in some detail. The necessity of study of the geology of the deposit and of probable costs is emphasized. Finally, the methods of calculating tonnages are outlined. DIAMOND-DRILL SAMPLING There are three main requisites for accurate diamond-drill sampling. First, the core should be removed and the hole cleaned out at the beginning of every sampling interval, usually 5 ft. (1.5 m.). After the rods are let down, water should be run through them until it becomes clear. The water must be clear before drilling starts. In this way the material knocked down from the sides of the hole by the descending rods is washed away, instead of being left to salt the sludge, sample.

Jan 2, 1922

By J. M. W. Mackenzie

Recent successful applications of emulsion flotation suggested that a detailed study of some of the physicochemical aspects of the process was warranted. The objective of the current research was to provide general information on the electrokinetic properties of emulsion drops of the type commonly used in oxide mineral flotation. Combinations of the parafin oil Nujol and several long-chain reagents in water were studied with respect to the effect of pH on the surface and zeta potentials. It war concluded that for emulsion drops in the presence of a long-chain reagent but in the absence of any other electrolyte which is adsorbed at the oil-water interface, the surface potential will be some two to four times the value of the zeta potential. During the last decade there has been a revival of interest in the so-called agglomeration, or emulsion flotation (in this paper the term emulsion flotation will be used), process. In this flotation technique, a neutral hydrocarbon oil, together with longcnain reagents, usually of a polar-nonpolar structure, are added to the pulp to function as collectors for specific minerals. The combination of oil and longchain reagent is either emulsified prior to addition to the pulp, or in the pulp itself, and the resulting collector species is an oil-in-water emulsion of a neutral hydrocarbon oil emulsified by polar-nonpolar long-chain reagents. Emulsion flotation has been used successfully in the treatment of ores containing iron, manganese,' and titanium oxides. 2 Two other major and long established applications of emulsion flotation are the flotation of coal and Florida phosphate ores. In recent years, emulsion flotation has been particularly successful in the treatment of ores containing oxide minerals which slime readily and, consequently, are difficult to treat by conventional flotation processes. The recent successful

Jan 1, 1970

By G. C. Gardner

A new correlation of blast penetration in model and operating blast furnaces is presented which overcomes objections to prevzous correlations. It is shown that the tuyere diameter is only of small importance in determining the magnitude of the penetration. The data from operating furnaces correlate satisfactorily with the data from models whose cross section is a segment of a circle. A bubble-shaped gas space called a "raceway" normally exists in front of the nose of a blastfurnace tuyere. The periphery or "wall" of the raceway is well defined and is composed of densely packed charge particles. The blast. issuing as a jet from the tuyere, entrains gas from the raceway, in the usual manner of a jet, as it flows to the opposing wall. There it divides and flows back around the walls to be entrained once more. The blast must, of course, eventually leave the raceway and pass up through the charge column, but before it does it may, on the average, make several circuits of the kind described and in doing so it carries with it charge particles, which, because of their fast and circulating motion, suggested the name of "raceway". A fuller description of the raceway may be found elsewhere."' Here it is only necessary to mention, in addition, the measurement which characterizes its size. If an iron bar is pushed through the opened peepsight of a tuyere, .as far as it will go with ease, it will be stopped by the relatively impenetrable opposing raceway wall arid the distance that the bar has been pushed from the tuyere nose is called the "penetration". This measurement may be of practical importance and has; been the subject, with considerable success, of several attempts at correlation with other variables2-5 as stated in the next section. There is still, however, a serious objection to the most recent correlation,3 which is overcome by the correlation proposed in this paper. It will be shown that the objection is not trivial, in that the new correlation will attribute considerably different importance to the variables affecting the magnitude of the penetration. The data to be treated were made available by Wagstaff and are the same as those used in his correlation. They include measurements taken on small models, in which a cold air blast was used and no combustion occurred, and they also include data from operating blast furnaces at Wheeling and Fairless. The information from the blast furnaces will be shown to be in substantial agreement with those models whose plan views are segments of a circle and which are thus like segments of a blast furnace. First, Wagstaff's most recent correlation3 will be discussed and the objection will be given. Then the new correlation will be developed and its implications considered. CORRELATION OF J. B. WAGSTAFF Wagstaff's correlation is where and D — the penetration D,-the internal tuyere diameter V —the blast velocity in the tuyere

Jan 1, 1961

By Samuel G. Lasky

In a recent discussion of the mineral resource position of the United States, published in the September 1946 issue of Mining and Metallurgy, I expressed my conviction that ore deposits of major magnitude remain to be found in this country and that they can be found without undue cost or risk. I stated with equally strong conviction, however, that if the search for such deposits is to be notably successful there must be, among other things, a reorientation of philosophy and mental habits on the part of many who would be connected with the search. I would now like to enlarge upon that statement. For such a purpose. we may consider that the search for concealed deposits involves four steps: (I) the selection of areas for further study; (2) the geologic study of those areas in order to verify their general favorableness and in order to choose specific patches worthy of being tested; (3) the decision whether exploration of the patches chosen should actually be undertaken; and (4) the exploration itself. The first two steps and the last rest upon the judgment and skill of geologists. The third step—the decision whether exploration should be undertaken—rests upon management. In my opinion, the philosophies or principles that have guided these steps in the past are now inadequate. Philosophy of Appraisal If concealed deposits are to be looked for, how are the places of their possible concealment to be recognized? Every known mineralized area still in the prospect stage has already been repeatedly examined and condemned. As for those deposits concealed under later rocks, there may be not even the clue of a near-by outcrop for engineer or geologist to consider. flow then, are we to know where to look? Geologic Probability In the early days of our mining industry, ore deposits were found mainly by "following the ore." Later, as such opportunities decreased, and as geologic concepts became accepted, deposits were found more and more through use of the notion of geologic probability. Many instances can be cited wherein a courageous operator ignored the implications of the unsuccessful efforts of predecessors and, solely by "following the ore," converted a discredited prospect into a good mine. Similar experience doubtless will occur in the future, but "following the ore" will no longer in itself find new deposits in the amount needed. Nor can enough new ore be expected from further use of the notion of geologic probability, for, as mentioned above, our known prospects have already been ex-

Jan 1, 1949

By Samuel G. Lasky

In a recent discussion of the mineral resource position of the United States, published in the September 1946 issue of Mining and Metallurgy, I expressed my conviction that ore deposits of major magnitude remain to be found in this country and that they can be found without undue cost or risk. I stated with equally strong conviction, however, that if the search for such deposits is to be notably successful there must be, among other things, a reorientation of philosophy and mental habits on the part of many who would be connected with the search. I would now like to enlarge upon that statement. For such a purpose. we may consider that the search for concealed deposits involves four steps: (I) the selection of areas for further study; (2) the geologic study of those areas in order to verify their general favorableness and in order to choose specific patches worthy of being tested; (3) the decision whether exploration of the patches chosen should actually be undertaken; and (4) the exploration itself. The first two steps and the last rest upon the judgment and skill of geologists. The third step—the decision whether exploration should be undertaken—rests upon management. In my opinion, the philosophies or principles that have guided these steps in the past are now inadequate. Philosophy of Appraisal If concealed deposits are to be looked for, how are the places of their possible concealment to be recognized? Every known mineralized area still in the prospect stage has already been repeatedly examined and condemned. As for those deposits concealed under later rocks, there may be not even the clue of a near-by outcrop for engineer or geologist to consider. flow then, are we to know where to look? Geologic Probability In the early days of our mining industry, ore deposits were found mainly by "following the ore." Later, as such opportunities decreased, and as geologic concepts became accepted, deposits were found more and more through use of the notion of geologic probability. Many instances can be cited wherein a courageous operator ignored the implications of the unsuccessful efforts of predecessors and, solely by "following the ore," converted a discredited prospect into a good mine. Similar experience doubtless will occur in the future, but "following the ore" will no longer in itself find new deposits in the amount needed. Nor can enough new ore be expected from further use of the notion of geologic probability, for, as mentioned above, our known prospects have already been ex-

Jan 1, 1949

A PAPER on "Iron and Steel Scrap in Blast-fur-nace Burdens," by W. C. McKee, general super-intendent, Federal Furnace plant, By-Products Coke Corp., Chicago, was published in the October issue of MINING AND METALLURGY, and written discussion by Richard Moldenke was published in the December issue. Following is the stenographic report of the oral discus-sion that took place when this paper was presented at Pittsburgh. J. N. REESE, Monessen, Pa.-I came to the conclusion that Mr. McKee must be using a poor grade of scrap, therefore his loss was high. Mr. Franchot said that there was ex-cess heat in the stack. There is no excess heat in the hearth, therefore, any heat that is used to melt this scrap must come from the stack. By using scrap in a blast furnace you can utilize this excess heat in the stack. The amount of scrap that can be used in any particular furnace involves a direct relation to the efficiency of that furnace. If a furnace is running on a very low-coke rate, you will not be able to use much; if on a high-coke rate, you can use considerable scrap, probably several times as much as that mentioned in these papers-without using any additional coke. This excess heat can be utilized with-out practically any serious mechanical and operating diffi-culties such as might be occasioned by removing gas from a point other than the top of the furnace. I do not think, scrap has any effect on the iron, although I think some foundrymen are trying to prove that it has, and perhaps some open-hearth men may have that idea.

Jan 1, 1927

By J. W. Marx, R. H. Langenheim

The authors are to he complimented for a timely presentation of useful information concerning application of heat to oil reservoirs to increase the rate and ultimate recovery of oil. The solution for heated area resulting from constant rate injection of a hot fluid, presented by the authors, and the fluid-flow analogy, solved by Carter,' are particularly interesting in that 110 restriction is placed on the direction of development of the heated area. It is not necessary that the heated area grow radially. Thus the solution could provide useful information for heat injection in any type of well pattern with any specified swept area data. However, it was assumed in the development that the heated region would remain at a constant clevatcd temperature. Vertical heat losses were computed on this basis. Physically. the assumption that the heated region will remain at a constant temperature (independent of distance from the injection point) appears to require that the heat injection medium be stcam, or other condensible gases near the boding point at injection pressure. If a hot liquid below the boiling point or a hot gas considerably above saturation temperature were used, the temperature of the heated region would decrease with distance from the injection well. Lauwerier2 has discussed this problem for a linear system. (See also Jenkins and Aronolsky; and McNiel and Nelson.') Thus, the authors' solution applies more nearly to steam injection than to hot water injection or hot, non-condensable gas injection. Assuming steam as the injection medium, it appears that steam would pass through the constant-temperature heated region and condense upon contact with the unheated sand. The tempcrature in the condensing region would probably be governed by the release of heat of vaporization required for phase equilibrium at the existing pressure distribution. Temperatures in the region would also be influenced by vaporization of hydrocarbon. Thus, it is doubtful that an expression for radial temperature distribution based on heat conduction only (such as the authors' Eq. 9) would have practical significance. As pointed out by Marx and Langenheim, the growth of the heated area under constant rate steam drive will eventually be limited economically by vertical heat loss. The possibility of continuing to move heat economically by cold water injection or by increasing the steam injection rate appears to be a very important consideration. (Movement of liquids away from the injection well should increase injectivity.) Fortunately, the solution presented by the authors may be generalized to thc case of a variable heat injection rate. The general solution is:

ANNUAL meeting of the Woman's Auxiliary of the American Institute of Mining and Metal-lurgical Engineers convened on Tuesday morn-ing, Feb. 20, the president, Mrs. H. W. Hardinge, presiding. President Hardinge, in opening the meet-ing, said: "I have the honor and great pleasure to welcome you to our seventh annual meeting. It has been a happy year, though I started in fear and trembling. My fear is partly gone and my trembling becomes less as time goes on. Never has a chairman had such splendid cooperation and harmony in her work; no. matter how much was asked nor what the task, I have always received the same answer, `We are with you, of course we can do it.' Often the road has been untried and the way full of snares, but we have all pulled together. Is it any wonder we have had a prosperous year? I cannot thank the governing -board and officers enough for their help." Mrs. Hardinge described her trip through the West last summer, during which she visited many of the local sections of the Auxiliary. She also spoke of the work of the Rossiter Raymond memorial library which has been started as an activity of the Woman's Auxiliary. Mrs. Reynders read the minutes of the last annual meeting, and Mrs. Kemp read the treasurer's report. The latter showed that on Feb. 1, 1922, there was a bank balance of $683.61 and on Feb. 10, 1923, the bal-ance was $947.93. Mrs. Westervelt expressed the sorrow of the Auxiliary for the death -of Mrs. Florence Howe Hall and of Mrs. Levi P. Holbrook.

Jan 4, 1923

By K. S. TWITCHEEL

THE different lines leading out from the vocation of a mining engineer are,' perhaps, the most' varied of all the professions. The expedition sent by Charles R. Crane of New York 'as a gift to the Imam Yahia, king of the Yemen, Arabia, was probably unique. Mr. Crane made a visit, in January,1927, to the Imam Yahia at Sanaa, capital of the Yemen. He was received with the utmost cordiality and respect, as his friend- . ship for the ,Arab world is famous; He was 'greatly impressed by the desire of the Imam to develop his country. The Imam stated that he had heard that there were minerals in his country and that he would like to secure engineers to advise him about them and other natural resources.. This seemed such a practical idea, and so greatly appealed to Mr. crane, that he offered to furnish an engineering 'expedition. Naturally the Imam gratefully accepted. This expedition was to study (as far as possible in 'the limited time) the natural resources of the ,Yemen, advise the Imam of what these consisted, and make suggestions regarding the most practical methods for their development. As agriculture is always such a fundamental part of a country's wealth, I first went to Indio, California, to study water-well drilling and the date industry, and eventually arrived at Hodeidah, the principal Yemen seaport, on Oct. 21, 1927.

Jan 1, 1929